Radios sold in North Korea are modified so they can only tune in to certain frequencies – government-operated North Korean stations, of course. But people do illegally “jailbreak” their radios, says Reporters Without Borders. They can then listen to South Korean stations near the border, or to shortwave foreign broadcasts like the BBC’s and similar ones from Radio Free Asia and Voice of America.

“North Korea does its best to stop the broadcasts coming in but it is the only way that exists at the moment to get current information into the country,” said Williams.

The North Korean government tries to limit what their citizens can hear. Radios can be modified, but a more effective way is to “jam” incoming signals. According to Williams, the concept is simple: the government will broadcast a whooshing or clicking noise over the same bandwidth to drown out the news.

The timeliness of Global's article is due to the launch this past week of BBC's new Korean service on 1431 kHz AM plus a few shortwave frequencies aimed at the north. The North Korean jammers are well-known to those of us who chase trans-Pacific AM signals in the wee hours of the morning. "whooshing or clicking noise" isn't quite right - more like outright blaring siren tones that constantly vary in pitch or "warble" at such a rapid & pronounced volume & rate, as to be very irritating on the ear & brain. These are quite distinctive & have been detailed & recorded for us here on the west coast by a prominent radio DXer in Seoul. Some DXers figure Pyongyang is cranking out 200-300 kW on some of the jammer signals received here & in Australia, along with their own broadcasting service which is heard often throughout fall & winter. North Korea also jams the south's TV signals & FM signals receivable just inside the border regions. Simply put, the mandate in N Korea is NO outside information or culture permitted.